This can either be regulated by the prices (only the rich can afford) or by the quantities (everyone is allowed a limited amount of travels in their life). I wish for the latter, but wouldn't bet much on it; having either would already be a big step. As for travelling, this could be the occasion of a big revisiting of what doing tourism means: it would still be possible to change continent once in a while, just not for the weekend. Trains can get your pretty far in Eurasia. Boats also need a fuel revolution but will hopefully get there.